1. Field
The present disclosure relates to a carbon nanostructure and a method for preparing the same. More particularly, the present disclosure relates to a carbon nanostructure obtained from decomposition products of an organic solvent and a method for preparing the same.
2. Description of the Related Art
The methods for preparing graphene quantum dots, one of the carbon nanostructures having a small size, may be classified into a top-down process including cleavage of a material having a larger size, such as graphite, and a bottom-up process including mixing carbon atom-containing organic materials.
First, graphite is a material in which graphene layers each having carbon atoms bound to each other in the form of a hexagonal cyclic structure are stacked. Herein, the carbon atoms forming graphene are bound through sp2 bonding and one graphene layer is bound to the adjacent graphene layer through Van der Waals bonding. Thus, it is difficult to cleave graphite into quantum dots having a small size. Therefore, according to the related art, a top-down process is used to weaken the bonding between graphene planes and layers and to produce quantum dots. For this purpose, graphene oxide is produced and it is subjected to hydrothermal reaction, thereby providing quantum dots. However, since such a method causes chemical oxidation of graphite structure in a strong acidic solution, the resultant quantum dots have poor quality. In addition, such a method requires multiple processing steps to produce graphene quantum dots and each step causes a drop in yield.
Meanwhile, a bottom-up process for producing graphene quantum dots includes subjecting carbon atom-containing organic materials to thermal or chemical treatment to control the size and to prepare quantum dots. Typically, an organic material, such as citric acid or glucose, is used as carbon precursor and quantum dots are prepared under high temperature/high pressure. Herein, depending on the particular organic material used for the process, doping with a heteroatom is performed. The resultant quantum dots show high production yield and high quantum yield. Thus, there is an advantage in that the resultant quantum dots show more uniform characteristics as compared to the quantum dots obtained by cleaving graphite. However, since byproducts are produced during the production of quantum dots, a purification process is essentially required and the quantum dots, once produced, are dispersed in a solvent merely in a small amount.
Under these circumstances, there has been an imminent need for developing a carbon nanostructure obtained by a simple process without production of byproducts and having excellent characteristics, and a method for preparing the same.